JP6489588B2 - Inductor and package including the same - Google Patents

Description

  The present invention relates to an inductor and a package including the same.

  In recent years, with an increase in communication speed, a smartphone (Smart Phone) has to transmit and receive signals in a wider frequency band. High-frequency inductors are usually used in impedance matching circuits in RF systems (radio frequency systems) that transmit and receive high-frequency signals, and the use of such high-frequency inductors is increasing.

  On the other hand, along with the downsizing of package products, the mounting area of passive elements such as inductors has been technically reduced, and further downsizing and thinning of passive elements is further required. At the time of manufacturing a package, an inductor is realized as a package together with an IC and a memory. At this time, a method of increasing the degree of freedom of mounting by forming the inductor into a mold package is considered.

  Inductors used for packaging include shrinkage generated when the insulating material is cured, shrinkage generated when the package is mounted and then reflowed, and the dimensions of the material with respect to temperature unit changes of each material. A large force is exerted by a mismatch of the coefficient of thermal expansion (CTE), which causes stress in the inductor and the inductor. This can cause product reliability problems.

  Therefore, there is a need for a method that can reduce the stress generated in the inductor during packaging and ensure the reliability of the product.

Korean Patent Application Publication No. 2014-0077347 Japanese Patent No. 3248294

  An object of the present invention is to obtain an inductor capable of minimizing the stress generated inside the inductor when packaging the inductor and ensuring the reliability of the product, and a package including the inductor.

  In one embodiment of the present invention, a coil portion is disposed inside, and a main body including a first surface and a second surface facing each other, a plurality of side surfaces connecting the first surface and the second surface, First and second external electrodes formed on third and fourth surfaces facing each other of the side surfaces of the main body and extending to a part of the first and second surfaces, and the first and second surfaces There is provided an inductor including a stress buffer layer disposed between a first external electrode and a second external electrode on two surfaces.

  According to an embodiment of the present invention, it is possible to minimize the stress generated in the inductor during packaging and to ensure the reliability of the product.

1 is a perspective view schematically showing an inductor according to an embodiment of the present invention. It is sectional drawing shown along the II 'line | wire of FIG. FIG. 5 is a perspective view schematically showing an inductor according to another embodiment of the present invention. 1 is a plan view schematically showing a package including an inductor according to an embodiment of the present invention. It is the front view which showed the package of FIG. It is the table | surface which showed the magnitude | size and direction of the main stress in the main body of an inductor at the time of packaging of a comparative example and an Example. It is the table | surface which showed the numerical value of the stress which generate | occur | produced inside the inductor at the time of packaging of a comparative example and an Example.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shape and size of the elements in the drawings may be enlarged / reduced (or highlighted or simplified) for a clearer description.

  FIG. 1 is a perspective view schematically showing an inductor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along a line II ′ in the inductor shown in FIG. .

  1 and 2, an inductor 100 according to an embodiment of the present invention includes a first surface S1 and a second surface S2 facing each other, and a plurality of side surfaces S3 connecting the first surface S1 and the second surface S2. , S4, S5, and S6, and the third surface S3 and the fourth surface S4 that face each other among the side surfaces of the plurality of main bodies, and extend to a part of the first surface S1 and the second surface S2. First and second external electrodes 81 and 82 formed, and a stress buffer layer 90 disposed between the first external electrode and the second external electrode on the first surface and the second surface.

  The main body 50 forms the appearance of an inductor. The main body may have one surface, another surface facing the one surface, and a plurality of surfaces connecting the one surface and the other surface. L, W, and T displayed in FIG. 1 respectively indicate a length direction, a width direction, and a thickness direction in a three-dimensional space where an inductor exists.

  The main body 50 includes a first surface S1 and a second surface S2 that face each other in the stacking direction (thickness direction T) of the coil layer, a third surface S3 and a fourth surface S4 that face each other in the length direction L, and It may be a hexahedron shape including the fifth surface S5 and the sixth surface S6 facing each other in the width direction W. When mounting on a printed circuit board, the second surface (other surface) of the main body can be a mounting surface. The angle at which each surface touches can be rounded by grinding or the like.

  The main body 50 includes a magnetic material exhibiting magnetic properties.

  The main body 50 can be formed by forming a coil portion, laminating a sheet containing a magnetic material on the upper and lower portions, and pressing and curing it. The magnetic material can be, for example, a resin containing ferrite or metal magnetic particles.

  The main body 50 may have a form in which ferrite or metal magnetic particles are dispersed in a resin.

  The ferrite may include a material such as Mn—Zn ferrite, Ni—Zn ferrite, Ni—Zn—Cu ferrite, Mn—Mg ferrite, Ba ferrite or Li ferrite.

  The metal magnetic particles include any one or more selected from the group consisting of iron (Fe), silicon (Si), chromium (Cr), aluminum (Al), and nickel (Ni). For example, Fe-Si It can be a -B-Cr amorphous metal, but is not necessarily limited thereto. The metal magnetic particles may have a diameter of about 0.1 μm to 30 μm.

  The resin may be a thermosetting resin such as an epoxy resin or a polyimide resin.

  The coil unit has various functions in the electronic device depending on characteristics expressed from the coil of the inductor 100. For example, the inductor 100 can be a power inductor, and in this case, the coil unit can store the electricity in the form of a magnetic field, and can maintain the output voltage and stabilize the power source.

  The coil portion includes first and second coil patterns 40 formed on the upper surface and the lower surface of the support member 20, respectively. The first and second coil patterns 40 are coil layers arranged to face each other with the support member 20 as a reference.

  The lead terminal of the first coil pattern 41 is exposed on the third surface of the main body, and the lead terminal of the second coil pattern 42 is exposed on the fourth surface of the main body.

  The first and second coil patterns 41 and 42 can be formed by a photolithography process or a plating process.

  The first and second external electrodes 81 and 82 are electrically connected to lead terminals of the first and second coil patterns 41 and 42 exposed on the third and fourth surfaces of the main body 50, respectively. .

  Referring to FIG. 1, the first and second external electrodes 81 and 82 are electrically connected to the first and second coil patterns 41 and 42, and lead terminals of the first and second coil patterns. Are formed on the exposed third and fourth surfaces, respectively, and extend from the third and fourth surfaces to a part of the first and second surfaces.

  The first and second external electrodes 81 and 82 serve to electrically connect the coil portion in the inductor to the electronic device when the inductor is mounted on the electronic device.

  The first and second external electrodes 81 and 82 may be formed using a conductive paste containing a conductive metal. As the conductive metal, at least one of copper (Cu), nickel (Ni), tin (Sn), and silver (Ag) or an alloy thereof can be used.

  The first and second external electrodes may include a plating layer formed on the paste layer.

  The plating layer may include any one or more selected from the group consisting of nickel (Ni), copper (Cu), and tin (Sn), for example, a nickel (Ni) layer and tin (Sn). Layers can be formed in sequence.

  Usually, the coil portion disposed inside the inductor includes a first coil pattern having a lead terminal exposed on the third surface of the main body and a second coil pattern having a lead terminal exposed on the fourth surface. In addition, the lead terminal, which is a connecting portion between the first and second coil patterns and the external electrode, has an asymmetric structure. Such an asymmetrical connection structure has a shrinkage force generated when the insulating material is cured during packaging, a shrinkage force generated when the package is manufactured and then mounted and reflowed, and the material dimensions with respect to temperature unit change of each material. The stress due to the change ratio (CTE) imbalance causes a large compressive stress to act on the inductor disposed inside. Such stress may cause cracks in the main body of the inductor and surrounding components, resulting in a problem that the reliability of the product is lowered.

  The inductor 100 according to the present invention includes the stress buffer layer 90 disposed between the first external electrode 81 and the second external electrode 82 on the first surface and the second surface, so that the inductor 100 is provided inside the inductor. Minimize stress and reduce the occurrence of defects such as cracks.

  Specifically, the stress buffer layer 90 may be disposed in a region on the first surface and the second surface except for the region where the first and second external electrodes 81 and 82 are formed. By dispersing the force when the contraction force is generated, the shear stress generated in the inductor and the inductor can be reduced.

  The stress buffer layer 90 is made of a highly rigid material, and can be made of a material having the same or larger rigidity than the first and second external electrodes.

  In the case of a highly rigid substance, the modulus, which is an elastic coefficient representing the ratio of stress to deformation, is high. Since the first and second external electrodes include a conductive metal, the modulus is larger than that of the main body including the magnetic material.

  However, since the lead terminals of the first and second coil patterns are exposed asymmetrically on the third surface and the fourth surface, respectively, the shear stress applied to the coil portion increases, and the crack generation rate increases.

  Accordingly, in order to reduce the stress applied to the body, the modulus of the stress buffer layer 90 may be equal to or greater than the modulus of the first and second external electrodes. Since the modulus of the stress buffer layer is high, generation of stress due to the asymmetric structure can be reduced.

The stress buffer layer 90 is made of a highly rigid material in which the first and second external electrodes are not electrically connected, and is made of, for example, one selected from alumina (Al ₂ O ₃ ) and silica (SiO ₂ ). be able to.

  In order to prevent stress from being concentrated on a predetermined region inside the inductor, the thickness of the stress buffer layer is the same as that of the first and second external electrodes on the first surface and the second surface. Can be formed.

  FIG. 3 is a perspective view schematically showing an inductor 200 according to another embodiment of the present invention.

  Referring to FIG. 3, the inductor 200 is electrically connected to the first and second coil patterns 141 and 142, formed on the third surface and the fourth surface, and the first surface and the second surface. First and second external electrodes 181 and 182 are formed to extend to part of the surface and part of the fifth and sixth surfaces.

  In the case of FIG. 1, the first and second external electrodes 81 and 82 are formed to extend from the third surface and the fourth surface to a part of the first surface and the second surface, that is, “U”. In the case of FIG. 3, the first and second external electrodes 181 and 182 are formed on the third surface and the fourth surface and the first surface, the second surface, the fifth surface, and the sixth surface. The one formed so as to surround a part is shown.

  As shown in FIG. 3, the first and second external electrodes 181 and 182 are formed to extend from the third and fourth surfaces to a part of the first, second, fifth, and sixth surfaces. In this case, the stress buffer layer 190 may be disposed between the first external electrode and the second external electrode on the first surface, the second surface, the fifth surface, and the sixth surface. That is, the stress buffer layer 190 may be disposed in a region excluding the region where the first and second external electrodes are formed on the first surface, the second surface, the fifth surface, and the sixth surface. .

  The support member 20 is not particularly limited as long as it can support the first and second coil patterns 40. For example, a copper clad laminate (CCL), a polypropylene glycol (PPG) substrate, a ferrite It can be a substrate or a metallic soft magnetic substrate. Further, it may be an insulating substrate made of an insulating resin.

  Examples of the insulating resin include a thermosetting resin such as an epoxy resin, a thermoplastic resin such as polyimide, or a resin impregnated with a reinforcing material such as glass fiber or inorganic filler, such as a prepreg or ABF (Ajinomoto). (Build-up Film), FR-4, BT (Bismaleimide Triazine) resin, PID (Photo Imageable Dielectric) resin and the like can be used. In terms of maintaining rigidity, an insulating substrate containing glass fiber and epoxy resin can be used, but is not limited thereto.

  The center portions of the upper and lower surfaces of the support member 20 are penetrated to form holes, and the core portion 55 can be formed by filling the holes with a magnetic material such as ferrite or metal magnetic particles. The inductance (L) can be improved by filling the magnetic material to form the core portion.

  The first coil pattern 41 and the second coil pattern 42 stacked on both surfaces of the support member are electrically connected through vias 45 penetrating the support member.

  The via 45 can be formed by forming a through hole using a mechanical drill or a laser drill and filling the inside of the through hole with a conductive material by plating.

  If the via 45 can electrically connect the upper first coil pattern 41 and the lower second coil pattern 42 respectively disposed on both surfaces of the support member 20, its shape and The material is not particularly limited. Here, the upper side and the lower side are determined based on the lamination direction of the coil patterns in the drawing.

  The via 45 is made of a conductive material such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pd), or an alloy thereof. Can be included.

  Vias are formed to electrically connect the first and second coil patterns formed on the upper and lower surfaces of the support member. At this time, the vias are formed by baking an interlayer insulating material by laser processing. Can do. When the via is formed, the thicker the support member, the larger the size. However, the larger the via size, the larger the volume of the coil. For this reason, the nonmagnetic region in the inductor increases, and there is a problem in that the current characteristic that the inductor should realize decreases.

  The cross section of the via 45 may have a trapezoidal shape or an hourglass shape.

  The cross section of the via 45 may have an hourglass shape. The shape can be realized by processing the upper surface or the lower surface of the support member, and thus the width of the cross section of the via can be reduced. The width of the cross section of the via may be 60 to 80 μm, but is not limited thereto.

  The first and second coil patterns 41 and 42 are covered with an insulating film (not shown) so that they are not in direct contact with the magnetic material forming the main body.

  The insulating film serves to protect the first and second coil patterns.

  Any material can be applied as the material of the insulating film as long as it contains an insulating material. For example, an insulating material used for a normal insulating coating such as an epoxy resin, a polyimide resin, a liquid crystal crystalline polymer resin, etc. A known photosensitive insulating (PID) resin or the like may be used, but is not limited thereto.

  Hereinafter, a package including an inductor according to the present invention will be described with reference to the accompanying drawings.

  4 is a plan view schematically showing a package including an inductor according to an embodiment of the present invention, and FIG. 5 is a front view showing the package of FIG.

  4 and 5, a package 1000 according to an embodiment of the present invention includes an inductor 100 disposed on a substrate, and an insulating material 1200 formed to surround the inductor. The coil portion is disposed on the first surface and the second surface facing each other, a main body including a plurality of side surfaces connecting the first surface and the second surface, and a third of the side surfaces of the plurality of main bodies facing each other. First and second external electrodes formed on the first surface and the fourth surface and extending to part of the first surface and the second surface, and the first external electrode and the second surface on the first surface and the second surface. And a stress buffer layer disposed between the external electrodes.

  The substrate 1100 may be a printed circuit board (PCB) in which a conductive pattern is formed on a plate made of an insulating material.

  In addition to the inductor, the package may further include a plurality of electronic components 300, 400, and 500 having different electrical characteristics.

  The insulating material 1200 may be an epoxy molding compound (EMC), and may be formed to surround the inductor and the plurality of electronic components.

  According to one embodiment of the present invention, after the inductor 100 is mounted on the printed circuit board 1100, it is formed so as to be surrounded by the insulating material 1200, and the influence of the compressive stress due to the insulating material when packaging is performed. In order to reduce the above, a stress buffer layer is disposed on the inductor.

  By disposing the stress buffer layer between the first external electrode and the second external electrode, the shrinkage and expansion force of the insulating material inevitably generated when packaging is distributed in the inductor and the inductor, It is possible to minimize the stress generated in the inductor and to ensure the structural stability of the inductor.

  FIG. 6 is a table showing the magnitude and direction of main stress generated in the inductor body during packaging in each of the comparative example and the example, and FIG. 7 shows the inductor in packaging in each of the comparative example and the example. It is the table | surface which showed the numerical value of the stress which generate | occur | produced inside.

  6 and 7 show the main stress and equivalent stress generated in the inductor body after the packaging process of the comparative example and the example, and the comparative example is an inductor in which no stress buffer layer is formed. The embodiment is an inductor in which a stress buffer layer is formed.

  Looking at the magnitude and direction of the main stress applied to the main body with reference to FIG. 6, in the comparative example, the directions of the stress received by the first and second coil patterns are different from each other, and the shear stress greatly increases at the intermediate point. The possibility of cracking was high. However, in the example, it can be seen that the stress applied to the inside of the main body is remarkably reduced because the stress relaxation layer supports the shrinkage force of the outside (insulating material).

  Referring to FIG. 7, when the equivalent stress portion applied to the main body and the external electrode is seen, in the comparative example, the stress is concentrated on the portion where the first and second coil patterns and the magnetic material of the main body are in contact with each other, and the crack occurrence risk portion Whereas the equivalent stress value of (A part) was 54.2 MPa, in the example, the stress was relatively relaxed by the stress buffer layer, and the equivalent stress value of A part was 45.2 MPa. It can be seen that the rate decreases.

  As mentioned above, although embodiment of this invention was described in detail, the scope of the present invention is not limited to this, and various correction and deformation | transformation are within the range which does not deviate from the technical idea of this invention described in the claim. It will be apparent to those having ordinary knowledge in the art.

20 Support member 40 Coil pattern 45 Via 50 Main body 81, 82, 181, 182 First and second external electrodes 100 Inductor 1000 Package 1100 Substrate 1200 Insulating material

Claims (14)

A coil portion is disposed inside, and a main body including a first surface and a second surface facing each other, a plurality of side surfaces connecting the first surface and the second surface,
First and second external electrodes formed on a third surface and a fourth surface facing each other among the plurality of side surfaces of the main body and extending to a part of the first surface and the second surface;
See containing and a stress buffer layer disposed between the first outer electrode and the second external electrode on the first and second surfaces,
Each of the first and second external electrodes includes a conductive paste layer formed on the main body, and a plating layer formed on the conductive paste layer,
The inductor has a rigidity of the stress buffer layer equal to or greater than a rigidity of the first and second external electrodes . The inductor according to claim 1, wherein a modulus of the stress buffer layer is equal to or greater than a modulus of the first and second external electrodes. 3. The inductor according to claim 1 , wherein the stress buffer layer is disposed in a region excluding a region where the first and second external electrodes are formed on the first surface and the second surface.   The first and second external electrodes are opposed to each other among the plurality of side surfaces, and are not formed on the fifth surface and the sixth surface connected to the third surface and the fourth surface,
  The stress buffer layer is not disposed on the fifth surface and the sixth surface,
  The inductor according to claim 3. 5. The inductor according to claim 1, wherein the stress buffer layer is made of one selected from alumina (Al ₂ O ₃ ) and silica (SiO ₂ ).   The inductor according to any one of claims 1 to 5, wherein a thickness of the stress buffer layer is the same as a thickness of the external electrode. The first and second external electrodes are formed to extend to part of a fifth surface and a sixth surface that are opposed to each other among the plurality of side surfaces and connected to the third surface and the fourth surface. The inductor according to claim 1 or 2 . The stress buffer layer, the first surface, the second surface, in the fifth surface and the sixth surface, the first and second external electrodes are disposed in a region excluding the formed region, wherein Item 8. The inductor according to Item 7. An inductor placed on the substrate;
An insulating material formed so as to surround the inductor,
The inductor has a coil portion disposed therein, a first surface and a second surface facing each other, a main body including a plurality of side surfaces connecting the first surface and the second surface, and the plurality of the main body First and second external electrodes formed on third and fourth surfaces facing each other and extending to part of the first and second surfaces, and the first and second surfaces. and the stress buffer layer disposed between the first outer electrode and the second external electrode in two planes, the saw including,
Each of the first and second external electrodes includes a conductive paste layer formed on the main body, and a plating layer formed on the conductive paste layer,
The package has a rigidity of the stress buffer layer that is equal to or greater than a rigidity of the first and second external electrodes . The package according to claim 9 , wherein a modulus of the stress buffer layer is equal to or greater than a modulus of the first and second external electrodes. 11. The package according to claim 9, wherein the stress buffer layer is disposed in a region excluding a region where the first and second external electrodes are formed on the first surface and the second surface.   The first and second external electrodes are opposed to each other among the plurality of side surfaces, and are not formed on the fifth surface and the sixth surface connected to the third surface and the fourth surface,
  The stress buffer layer is not disposed on the fifth surface and the sixth surface,
  The package of claim 11. The package according to claim 9, wherein the stress buffer layer is made of one selected from alumina (Al ₂ O ₃ ) and silica (SiO ₂ ).   The package according to any one of claims 9 to 12, wherein the insulating material is made of epoxy molding compound (EMC).